So-called multi-mode terminals are being developed as mobile terminal devices that are connectable with a plurality of wireless schemes such as long term evolution (LTE) and wideband code divided multiple access (W-CDMA) schemes. A method called “fast redirection”, for example, has been disclosed as a technology used for changeover among a plurality of wireless schemes.
A brief description of fast redirection will be given below.
In fast redirection, first, a mobile terminal device reports a connection request and wireless schemes supported by the mobile terminal device to a base station of the first wireless scheme.
Then, the base station of the first wireless scheme determines whether a second wireless scheme is included in the wireless schemes supported by the mobile terminal device, and whether a base station of the second wireless scheme is located near the base station of the first wireless scheme. If it is determined that there exists a base station of the second wireless scheme that satisfies the conditions, the base station of the first wireless scheme prohibits wireless connection with the mobile terminal device, and notifies the mobile terminal device of the center frequency of the transmission band of the base station of the second wireless scheme.
Then, the mobile terminal device detects the base station of the second wireless scheme by using the center frequency of the transmission band of which the mobile terminal device has been notified from the base station of the first wireless scheme. Then, the mobile terminal device establishes a connection in a wireless manner to the base station of the second wireless scheme.
In a multi-mode terminal according to an example of the related art, separate tasks in one processor are assigned to a plurality of wireless schemes. For this reason, if an interrupt that triggers reset processing occurs during communication, the communication will be stopped until the processor completes reset processing. In other words, although the mobile terminal device supports a plurality of wireless schemes, communication is stopped when a processor starts resetting. Communication reliability has not been ensured.
Japanese Laid-open Patent Publication No. 2010-245888 is an example of the related art.